My advice to you is to return the personal cheque to whoever sent it to you and request that they do an international bank transfer to your account.
A UK bank is not going to cash a personal cheque for 5000 dollars drawn on a US bank where
1, The don't know whether the cheque is forged
2. They don't know there is sufficient funds in the account
3. They don't know whether the cheque has been countermanded.
What they will do is either negotiate it or collect it.
They will only offer to "negotiate" it if you are a good customer and they know that you would be good to repay them 5000 dollars should the cheque be dishonoured. Essentially while the cheque is going through the system they have advanced you the monies at a certain rate. Also you will have incurred bank charges on top of that.
Now if the cheque is dishonoured in due course you will be debited for 5000 dollars at the rate applicable at the time of dishonour. Therefore you could lose more than you were given in the first place!
If they collect it, you receive absolutely nothing until the cheque has gone through the system which can be weeks, and the cheque has been honoured by the US bank. You will get the rate applicable at that time, not the day that you pay it in.
A personal cheque is the worst way to receive monies from abroad!
Now eventually when you get the monies, if you have it dominated in another curreny rather than sterling, you will have two bank margins to pay - eg the difference between the selling and buying rates to convert for eample dollars to euros, and secondly the difference in the buying and selling rates to convert the euros into sterling - you will have to be the judge whether you think the exchange rates will appreciate enough to offset the double whammy!