London in April or June

We were in London last year in late March. We had medium-weight jackets, but no need for a parka. Unless you’re chilled to the bone with anything cooler than 60 degrees Fahrenheit, it shouldn’t be too cold in April.
We stayed at the 122 Great Titchfield Street B&B, and actually in their “suite” with its kitchen, and are staying there again this year: http://bb-london.co.uk/ . They loaned us umbrellas, but those weren’t actually necessary when we were there.

April can be really cold in London. I was there the last week of April 2018, and was not prepared for it. Took the Eurostar to Paris, and enjoyed shirt sleeve weather for the remainder of my trip...I would choose June, say the first half of the month before the tourist horde descends...

Meanwhile, I loooove visiting London in April. Love being there in Spring.

April hoping flowers are in bloom.

Can be chilly. Can be sunny.

Dress in layers.

The King’s Coronation is on May 6. Preparations for the event will take place in late April so keep that mind. Union Jacks being hung. Stores and shop windows will be dressed. Nobody does better at preparing for large Royal festivities than the British.

I’d go in early April.

As far as hotels look at the Premier Inn Chain.

IMHO both County Hall and Victoria PI’s are convenient for first time visitors. County Hall is next to Jubilee Gardens and across the Thames from Parliament. Pleasant stroll across Westminster Bridge towards Parliament will remind you aren’t “ in Kansas anymore.”

Look at 63 Bayswater or Vancouver Studio Apartments.

63 has an elevator is across the road from Hyde Park and 15-20 minute walk from Paddington Station.
Breakfast is included in the price. 1/2 block from Lancaster Gate tube station.

Vancouver Studios are in the Bayswater neighborhood and 25-30 minute stroll from Paddington. Kensington Palace is 20 minutes away.

You’d be unlucky to get cold weather in April but it can happen! Even in June you could get unlucky with rain although it would not be very cold by then. Either month would be a good choice.

June would be best.

Try Hotel 63 which was recommended to me and I booked for October. Small 16 room bed and breakfast facing Kensington Park, near Paddington Station and Lancaster Gate station.

Booking.com is a good site to both do research as well as book but you can also go directly to the hotel website to book.

April is right around the corner. Planes and hotels are probably going to be expensive but June is vacation season so planes and hotels will also be expensive.

Easter might also cause conflicts for your travel whenever Easter is.

Umbrellas can get blown away in the wind, but are still sometimes worth having. Carry a small one! Keep moving, or you risk hypothermia. I am not joking here, cause I have had it twice (nobody ever accused me of being very smart). Be ready to boil over in the tube or a bus if you dress too warmly, otherwise. But it WILL rain; how much or for how long, is anybody's guess.

As for accommodation: I like to stay on a direct tube line to Heathrow, cause that it where I land, normally. Piccadilly Line Tube/Underground (don't call it the "subway", for them, that is an underground sidewalk that goes under a road). Just limit your baggage and make life easy. Rooms can be quite small by North American standards.

I usually go to the UK every June and have been lucky with good weather. Flowers are in full bloom and the daylight hours are longer. However, considering the cost of a flight to London these days. I would be tempted to go in April this year. London should look lovely with the preparations for the King's Coronation. If you decide on early June, remember Whitweek (Monday, May 29th) will mean schools will be out for a week-long vacation. You may want to avoid that week.

It would be helpful to add your location to your profile. This is also a pretty interactive forum so input back from you is helpful to "us" to give you more tailored answers.

I'd go for April too! June can be too hot for me but I live in North Idaho and am not heat tolerant.

If you don't have physical restrictions with your hotel budget you might look at The Lime Tree on Ebury Street. They do not have an elevator so you'd need to carry your bags upstairs. It's a family run smaller hotel that was just refurb'd during the pandemic. I like that they have a 24 hour front desk and that they know who is coming and going.

"Hidden gems" are hard as we don't know what you are interested in. London Walks (walks.com) are excellent. I like the smaller museums like the Wallace Collection BUT in April there are special exhibitions at both the National Gallery (After Impressionism) and the Queen's Gallery (Dress in the Georgian Era). Both interest me but neither might be your style. British Library is a location that not as many people visit if you are interested in old books, texts, manuscripts etc.

I’m debating going in mid April in between Madrid and Barcelona.

I went to Wimbledon (late June) it rained one day was in mid 80s super warm (no AC) but was still chilly in morning (60)

how much research have you done already, and what questions did it trigger?

I'll be there April 8th through April 17th staying at the Hub by Premier Westminster Abbey ... hoping for a nice spring with not too many rainy days.