New to the table, so no reads.
I have £50, XX had £40
I am in SB with
UTG folds, XX Raises to £2, Cutoff(CO) calls, I call, BB folds
Flop:
All check (pot 6.50)
Turn:
I check, XX bets £2.00, CO calls, I raise £10, XX calls, CO folds. Pot 27.
River:
XX bets 23.
What do you do, and what do you think he had, and how did i play this hand please?

You had position and great hand on flop, you should have used it IMO. Bet on flop as it really looks it hit at least one villain in there with you. Also, your raise on turn is too small. Reread the post where you ask about bet/raise amounts.

Looks like a suited connector of some sort. That or nothing. Less likely hands are AA, QQ, AQ, AK. The river bet indicates either a flush value bet or a bluff, but could also just be aces up. I'm assuming you checked the river, right? If so, I'd call here given the range of hands, and the fact that a check is likely to induce a bet from weaker hands.

I lead flop. If I don't lead flop, I lead turn. If I check/raise the turn, then I lead river with a blocking bet of 10 or so.

[quote="RedBarracuda"]You had position ...quote]

I was first to act, so I was out of position surely?

PS: Yes I checked the River first before XX's bet