Train reservations

It's not compulsory to have a seat reservation, but if you don't you may well end up standing, plus the cheaper Advance tickets include a seat reservation.

https://www.virgintrainseastcoast.com/

Two minute walk between KGX and STP

St Pancras and Kings Cross are literally across a street from one another, but remember that Eurostar has a check-in deadline of 30 minutes before departure due to its airport-style security and ID checks.

Although the two stations, Kings Cross, and St Pancras International are side-by-side, allow time for your train from the North to be late, and I always suggest now to be checked in no later than an hour before departure at Eurostar. You have to go through security, then British Border control and then French border control before you get to the departure lounge.

Free wifi at Eurostar - in fact in all of St Pancras International, and there are many many charging points and laptop stations in the departure lounge, as well as a Caffe Nero and a WH Smiths, and a Paris counter.

Dozens of eateries in both St Pancras International and Kings Cross, as well as take aways for sandwiches and bottles of drink, alcoholic and non.

Be aware that you are not permitted to take open containers of drinks through security - I had to guzzle a very hot cup of coffee once - but bottles and unopened cans are (were) permitted. You can always load up at the departure lounge WH Smiths, too.

Eurostar are exceedingly picky about making check in times.

Not my intent to hijack this thread but I have a related question. I purchased all my longer train trip tickets in advance. For many of my journeys, it said "reservation not available" when I got confirmation emails. I was only able to make a reservation on one train. It was a CrossCountry train. The others....Southern and ScotRail did not allow me to reserve a seat. Does this mean I might have to stand? No way can I stand for more than 10 minutes. Should I contact ScotRail and Southern and tell them? I purchased what I thought were First Class but non-refundable tickets on most legs.

Only some trains and train companies offer reservations, usually on more premier and longer distance trains.

Most companies don't offer reservations on most trains and many actual trains simply have no facility for them.

Much of Southern Trains stock is fairly old, even the new stock only have 12 to 24 first class seats per 4 car train segment - all the rest are standard class. The ticket is to get you from an origination station to a destination, but does not guarantee a seat.

Most of Scotrail services are local trains with no reservations either.

If you are told that reservations are not available I suggest that you avoid rush hour trains.

If you share what routes you are traveling on perhaps other words of wisdom may precipitate.

Without knowing what your journeys are, it is impossible to tell if they are routes where reservations are never available, or ones where the reservations have all been taken. Looking at the companies it is probably the former.

On services with reservations there are unreservable carriages.

Here are very approx.times (not exact) that I would board the trains and thank you in advance for your thoughts. (NR)=No reservations available. These are all weekdays/work days except where indicated.

Woking to Havant(NR)
11:30am

Havant to Horley (NR)
14:00

Glasgow Central to Edinburgh Haymarket (Reserved)

Edinburgh Haymarket to Glasgow (NR)
16:30

Glasgow Queen to Inverness (NR)
9:30am

Inverness to Edinburgh Haymarket
9:30am

I hope you haven't paid for first class tickets to and from Havant, an unusual destination in itself? The trains from Woking to Havant are at least every 30 minutes and take around 45 minutes, first class is barely distinguishable from standard class, I use the line regularly, you would have no difficulty finding seats. Edinburgh to Glasgow is another short journey, trains every 15 minutes or so, plenty of seats except at rush hour.
The two longer trips might justify first class if they were to and from Edinburgh as some of the East Coast services have decent First Class seats with free food and drink included in the price but from Glasgow the trains are far less spectacular, if you have paid first class you may get a free coffee depending on what time of the day you are travelling, you should check at www.scotrail.co.uk, as a general rule, catering is poorer or non existent at the weekend

I just double checked. I have seat reservations on the Cross Country train. The routes where my ticket says "First Advance Single" are Inverness to Edinburgh and Glasgow to Inverness. However, none of the routes allowed a reservation for a seat except the Cross Country trains.