Yes, its 64 bit.

I remember asking if there was an option to build more RAM into it when I bought it, 3 years ago, and I was told at the time that it could be increased to 8GB.

When I take it to be cleaned next time I will ask them to check for hardware faults, and also how much it will cost to have the extra 4GB RAM while they've got it in bits on the bench. Again, though, that's not going to happen until after Christmas.

I'm kind of hoping to maybe put all my Christmas money together and be able to afford to part exchange this one for an altogether better machine

What an interesting site that is! If I had the money I'd be half tempted to get all the best bits and build my own from scratch