I'm a little confused too. It doesn't really sound like a cash game if you buy in for 5 Pounds and get 2000 in chips. It sounds more like a tournament.
In a cash game, you buy-in for $20 and get $20in chips, for example. The chips are equivalent to cash in this example.
In a tournament, you buy-in for $20 and get T5000 in chips, for example. The chips have no cash value in this example.
I guess not feeling like you have a stack with only 2000 in chips depends on the blinds that are being used. If they start at 100/200 then yes, I'd say your starting short. Then again, everyone starts with the same amount (I can only hope

) so at least everyone's on the same page.
After looking at the OP again, it looks like 100/200 would be the starting level based on the denoms being used.