...is living away from home really expensive, I pay rent at home, for sky (which I will be stopping), the internet, etc etc.
It will depend on how much you pay in rent compared to how much you have to pay for a mortgage. We became first-time buyers just before Christmas, and we found a lovely little house for which we're paying a little less than the rent on our old flat.
What you and your sister need to do in terms of the finances is look at how much you can afford to pay each month and (although it sounds obvious)don't go for a property that's beyond your means. One thing to consider is transport – is it just as easy to get to work/town from your potential new pad as it is from where you currently live? If it's a longer journey then it can be quite surprising how the extra transport costs can rack up. Don't forget either that even a fairly new house is still going to need a bit of work to get it exactly how you want it, even if it's something as simple as a fresh lick of paint. And make sure you find out about the local council tax and what band the property falls into.
It's always a good idea when you go to look at a property to take someone along who's got some experience of buying a house – maybe a parent. It's surprising what they pick up on that you overlook.
On the subject of parents – even if you don't have any kids it's an idea to find out about the local schools. Obviously if you have a kiddie or two in the future it's a plus point, but even if you don't if you're in the catchment area of a really good school then that's a very saleable and attractive feature when you come to sell in the future.
One other thing – obviously it's going to take a while to find your house, but be aware that after June 1 anyone who sells a house has to have a
Home Information Pack for the property. It's going to cost hundreds of pounds for a seller to get the pack put together for a property, so if you buy after this date then the seller has to do the work for you (ie, if you sell the house in ten years time you'll already have your pack sorted, it'll just need updating which is going to be easier and cheaper than starting it from scratch).
Good luck!