I"d probably shove it all-in to be honest. Essentially this is going to be your remaining 11,200 (13,000- 1,800) to win 21,800 (SB"s 8,000, BB"s 12,000 assume he"s pot committed - and your initial raise of 1,800) so nearly a 2/1. There"s only QQ, KK, AA that beat you, anything else you"re in great shape. Even if they HAVE one of those three over-pairs you"ll suck out on them 20% of the time anyhoo.
Granted I"m factoring into this decision that"s it"s a £12 buy-in and only two places get paid. I assume the blinds are 15-20 minutes? If you win this pot you knock two players out plus the chips you have now will give you license to steal anything not tied down...so indirectly it"s a potential pot of even more than 21,800. You only live once man, shove it in... BANZAI DANIEL SAN!!!