Hi there, welcome to the forum!

So what receiver should I get, I take it the lemon Rx ones I've used for antweights won't be beefy enough but don't really know?
I use something like this in my Featherweight (https://hobbyking.com/en_us/orangerx...er-w-cppm.html) which works well. I guess you'll already know this but you'll need to match up the protocols between your transmitter and receiver (DSMX transmitter, DSMX receiver and so on).

I use a pair of LemonRX DSMX receivers in my Middleweight bound to the same transmitter for my drive and weapon as an aside (https://www.ebay.co.uk/itm/262538900148) which have been immensely reliable.

got some 50amp ESCs(should be ok?)
I presume these are brushed ESCs from the overall description? They'll be easier to get started with. The motor will only ever draw as much as it needs so provided that the draw from the motors isn't above 50A (which drill motors realistically shouldn't under "normal" use), that should be OK.

To add, your battery, if a LiPo, will need a fuse in the wiring loom rated below the burst rating of the battery to meet the FRA rules. You'll also want a power light to show the robot is powered up and a removable link to turn the robot on and off. Hope this helps.