Traded Options in TMC don't exist on LIFFE: in fact, you have to be a larger-cap ftse100 stock to have these.
I suppose you could arrange a spreadbet in TMC, but would need to be an established client of a larger firm; also, the margin would be pretty substantial.
CFDs in TMC don't exist (I think). Nor CWs.
Borrowing stock to sell short - again, you need to be an established broker client with a very deep pocket.
So most of the posters who "have taken short positions" in TMC are fantasising - the only shorts they are in are trousers.
I'm surprised that all the serious and informed posters here have bothered giving time-of-day to these new arrivals.
[Have held some of these since August - not enough to make me rich ... or poor]