Driving from Heathrow to Nottingham?

It really depends...If you plan to do driving the entire trip and return car to Heathrow on your way back I would rent the car and drive the 2.5 hours up the M1 Motorway.
If you plan to stay in Nottingham area and won't have the need for a car then I would take the train. 50 GBP for 2 people but you need to go London St Pancras on the tube then catch the train to Nottingham. Its not that hard to do but with a lot of luggage the tube can be a little tricky. If you take the train out of Heathrow instead of the tube the price jumps to 182GBP! I am sure there are plenty of blogs about trains and tubes etc.

If you have read my answers to others on various topics I don't tend to sugar coat things, I tell what things are from my experience.

If you stay near the airport and drive the next day, wait until after the rush hour or you may as well just park the car. If you hit no traffic - ha! - or construction delays - ha! - the 135 miles will take you around 2 and a half hours after you get the car.

However, expect slow to very slow traffic on the M25 immediately you join it, sometimes back onto the slip road from the M4, all the way until past the M40 junction. There is a rebuild happening of the viaduct over the canal and railway at Kings Langley, and there is often a backup a little further ahead.

Don't be confused by the junction of the M25 and M1, just follow the signs and ignore everybody flying through it like they know what they are doing. One lane off becomes two, then the two lanes becomes three for the slow slip road and one lane goes off to the right for faster slip road which becomes two or three and then quickly merges onto the M1 then the other slow slip roads merge, then it all goes down to 4 lanes, then it often stops. Just go with the flow (or not), and after a while it will sort itself out.

Expect speed restrictions, camera controlled on the variable speed area around Luton - often for no apparent reason other than running the cash up - and then you are good until the construction north of Luton for the new interchange. If it says do 50, do 50. Speed averaging cameras in the roadworks.

Oh speaking of speed on the M1 - the different lanes will have dramatically different speeds, especially the high speed train of white vans and SUVs (and Audis) in the fast lane. Don't interfere with the high speed lane unless you know exactly what you are doing, and prepare for sudden stops.

Then you are OK until Flitwick where there is usually a collision in the London bound carriageway which screws things up on both sides, or you may get one in the northbound carriageway if you are particularly unlucky.

There are moving roadworks between Junction 13 and somewhere north of Junction 16, watch out for speed restrictions and lots of cones.

There is construction north of the junctions for the M6 and A14, and more construction on the road into Nottingham.

If it were me I would leave an extra hour for en-route delays.

By train, simple 54 minute Tube to Kings Cross St Pancras (no changes, lifts and escalators both ends) the a direct train to Nottingham from St Pancras, no changes.

We plan on having a car for most of the trip so we would prefer to drive if we can. Can you tell me what the peak hours are for traffic?

Maybe we can try to go when things are not too crazy. Thanks.

As an alternative there is a direct coach, with a more or less hourly timetable through much of the day.

Can you tell me what the peak hours are for traffic?

It’s always busy. I’ve been stuck in traffic jams caused by roadworks on the M1 just north of London at 1am before now.

Absolute peak hours are probably 7-10am and again maybe 4-7pm but it’s busy all day.

Agree with Jane.

Recently it has been extremely rare for me to make the journey between Northampton and Heathrow - I usually go beyond Heathrow - without some sort of additional problem beyond the construction causing a backup. Day or night, mid-day or morning, it doesn't matter anymore. It is just that between 6 and 10 in the morning - 6 or 7 days a week now - and 3:30 to 8 in the afternoon, it is even worse.

My checking of the train, STP to NOT is £19 pp singles Advance (no alteration) or £64 pp Super Off Peak Returns. Get a £30 Two Together Railcard (1 card for 2 people) and knock 1/3 off those prices. Train is 1:40, give or take plus an hour for the Tube and £3.10 (Oyster or Contactless after 9:30 M-F) or £6.00 cash, pp.

I don't want to dissuade you, just show you the reasonable options.

Will you be in Nottingham itself, or nearby? Where will you be going to in the car? I know the area fairly well.

We will be attending an event in Nottingham so will be spending a few days there. Then we want to go visit York, the Cotswolds, Bath and surrounding area and then finally London. I thought that with all these stops, it will be easier by car, especially in the Cotswolds. We plan on returning the car before London.
Based on the suggestions, I think we will take the train out to Nottingham and then pick up a car there. Thanks.

We actually found the M roads easier than in-town driving with roundabouts. Find the slow lane, maintain a proper gap between yourself and the car in front of you as much as possible, and have GPS/sat nav on hand so you can figure out any needed lane changes a mile or two ahead of time and it wasn't that bad.