Get the flysky gt5,it will come with 1 receiver. So that's covered. You can use any nimh 5 cell 6v flat battery pack, say 3000mah +/- or so.
Then you'll need a charger,tons of chargers. Here's an example:
1:
Flysky FS GT5 6CH AFHDS RC Transmitter with Flysky FS-BS6 Receiver For RC Car Boat:
https://www.amazon.co.uk/Transmitter-Receiver-Control-Protect-Setting-GT5-Transmitt/dp/B07C715SJW
1: HTRC C240 DUO Charger -
It's AC/DC charger - (so it can be used in car or home):
https://www.amazon.co.uk/Balance-Ch...s=HTRC+C240+DUO+Charger&qid=1593548532&sr=8-1
1:6V Flat Nimh battery Pack:
https://www.amazon.co.uk/Traxxas-30...+NiMH+Flat+Battery+Pack&qid=1593549551&sr=8-4
(This battery is just to show what type you need,you might be able to fit a hump pack in somewhere as there more plentyfull and have larger capacities. I only looked on Amazon.uk.)
I'm in the US,so prices are going to vary.
I don't know your hobby shop so, see if you can get them all from one place to make it easier.
Maybe evvs or Doug

or any other uk'er can help tell you where the best place to purchase these items or bigger battery pack.