I mailed a toy I sold on ebay last week first class and as far as I know the buyer hasnt recieved it yet (they are in the UK too) , so it wouldnt surprise me if some places in the Uk still have delays. I'm waiting on some parcels that are late arriving here too. Holidays here generally cause some delay
A few years back I had a couple of items take 3 weeks to get to Wales
i could have hand delievered them in like 2 1/2 - 3 hours
I do understand why you are worried though
has the person you mailed it to been here/ sent any messages to say it hasnt arrived yet? or is there a possiblity that they could have got it , but they havent been on the arena for a few weeks?