Should I pre-purchase rest of tickets?

I would. We saved at least an hour by having our pre-purchased tickets at the Churchill war rooms this summer.

Yes! We avoided very long lines at Windsor Castle and the Churchill War Rooms recently by pre purchasing our tickets.. We were moved to the head of the line in both venues. I imagine Hampton Court is similar but skipped it this trip.

We went to London this time last year and visited Tower of London and Hampton Court without pre-purchasing tickets. We arrived at both attractions around the time they opened and didn't encounter lines of more than 15 minutes. If you plan on arriving early then I don't think it's really necessary at this time of year, but I guess it also can't hurt.

We were able to do a National Rail 2 for 1 deal for Hampton Court so you might want to check into that. That deal is on for the week you will be there. Those are walk-up and not available for pre-purchase for that attraction. You have to have a qualifying rail ticket and fill out a voucher....we didn't know about the voucher but were able to fill one out at the Hampton Court Palace ticket desk. https://www.daysoutguide.co.uk/hampton-court-palace

About qualifying rail tickets: https://www.daysoutguide.co.uk/travel-by-train/is-my-ticket-valid-for-2for1

Thank you for the responses.

My family and I visited England for the first time this summer. We pre-purchased our tickets once we arrived in England from our flat, either the night before, or even morning of our trips to Windsor, Churchill War Rooms, Kew, etc., and we got all the perks of pre-buying. That said, our phones were up and running just fine and we were able to show our vouchers on them. The bonus for us in waiting until the night before or morning of was that we found we had to adjust our itinerary a bit throughout our trip, and this gave us some freedom...

Also -- whichever way you decide to go with pre-purchasing (in the US or in England) -- make sure you head over to someone who works at the attraction right away and tell them you pre-purchased. It's not always clearly marked that there's a separate line and you could end up waiting for the same amount of time as everyone else for no reason! This was definitely the case at the Churchill War Rooms where there was just one huge line. When we told them, they took us all the way up front and lifted the rope and let us go in ahead of everyone!

Thanks Elizabeth. Good to know about letting venue employees know we already have tickets.