I want to be able to get a mortgage before I turn 21, so I've got 3 ish years.
I'm looking at properties and mortgage calculators very regularly and with what figures I've put in, it gives me an estimated monthly payment of around £500-700.
I'm working full time and will be putting away £400 minimum each month from my wages, giving my Mum £250 for rent and then I should have about £400 to 'play' with. I am going to go and try and spend a lot less than I have been, thus enabling me to save a bit more each month.
I am going to aim to save £12k within two years, and then see where to go from there. I am seriously confused as to how I go about getting a mortgage? It's such a stupid question but do i apply online, or do I go into my bank? I don't understand. 
Additionally, I would like to know the best way to build credit. I've never borrowed money like that, or been in debt. I'm not keen on the idea of credit cards, or high interest department store cards. I have looked on Very and saw their Take 3 stuff, but i am so uninformed on these things. Does Very count as building up credit?
TIA (Sorry it's so long!) 