Hold on old chap - You mentioned that you want to run the tank indoors over winter. Be careful with metal tracks - they can really score your flooring up if it's wooden and can lift carpet in a turn. Also, remember these are mechanical machines and have grease and oil in them in various places which can also make a mess. For an introduction to RC tanking both indoor and backyard running, the standard newest HL tanks will more than suffice. The T90 is indeed a good option but any of the latest HL tanks (Challenger,Abrams,) are all good as standard.

Good luck

CaptB