Well, you know what Kirsty and Phil say! Get on the ladder as soon as you can walk!! ;-)
Firstly, have you spoken to a mortgage advisor and got your finance sorted? What I mean by that is - do you have written confirmation from them that they would be willing to offer you a mortgage to the value of £100-120k? If not, and if you are just guessing what you can afford, you need to make an appointment to speak to a mortgage provider. Speak to a few! Shop around :-) You will need to have your finances sorted by the time you make an offer on a place anyway - the agent will want immediate proof that you have been granted permission for a mortgage of a certain amount, so getting something in writing now will get you a step ahead. Get them to put something in writing for the maximum mortgage they will give you - that way, if you see something cheaper, you've got proof that you can easily get a mortgage for that amount.
Next, if you haven't already, you'll need to work out what the mortgage repayments will be. Google 'mortgage repayments calculator' to get an idea. A good one is this:
Once you've worked that out, you need to budget on paper. Write down literally EVERYTHING that goes out of your account - include socialising, food shopping, smoking (if you smoke), clothes and a savings allowance. You always need money left over to save - even if it's only £50 a month.
Just because a mortgage provider will give you a certain amount, it doesn't mean you can physically afford it. Alliance and Leicester will give my boyfriend a mortgage of up to £220k.. but when we worked it out on paper, he could actually only really afford £190-200k. That's why it's best to work it out for yourself once they've approved your finance.
If you've already done all this, or when you've done it, then I would say go for it. £20k isn't that low of a salary. Teachers earn £25k to start with! I've just finished uni and i'm looking at jobs for £13k - my mom has spent 15 years on £13-18k. £20k is a reasonable wage hun.
In short - if you can actually afford the mortgage repayments as well as everything else you need, then go for it.
Of course, the other option is to look into a 50?hared ownership. You can read more about this here:
And here is a website that is very helpful for first time buyers such as yourself!