(2-part post):
If you've described the injuries accurately, you shouldn't be facing GBH charges, since a broken nose, minor cuts and bruising all fall within the Crown Prosecution Service's definition of ABH, rather than GBH. You can read the definitions for yourself, here:
http://www.cps.gov.uk/legal/section5/chapter_c .html
If you've not already been charged, expect the charges to be under 'Section 47' (ABH) rather than Section 18 or Section 20 (GBH). If you've already been charged with GBH you need to seek to get the charges dropped down to ABH. For that you need to engage the services of a solicitor, which probably won't cost you a penny.
ABH is a 'either way' offence, which can be heard in a magistrates' court or in the Crown court. You'll automatically qualify for legal aid in a magistrates' court if your gross annual income is less than �12475 or if you're left with less than �3398 per year after paying tax, national insurance, all housing costs and deducting a living allowance. (Those figures assume that you're single and not supporting any children). If the case is heard before the Crown court, you're entitled to full legal aid irrespective of your income. (Even if the magistrates didn't send the case to Crown court, you have the right to insist that the case is heard in a Crown court, before a jury, so you'd automatically be entitled to receive full legal aid).