Check out britishmilitarysurplus.co.uk
They do a great deal for shirt, trousers and smock in DPM or DDPM for £25 which is a good way to get a basic set of clothing. They also have boots at good prices. While you're at it, get a hat, scrim scarf or shemagh. You will also want gloves. The most painful places to get shot are Hands, head, ears and neck.
With regard to load carrying, there are lots of options. Tactical vests tend to be very adjustable so you needn't worry about sizing. Webbing and Molle both allow customisation of which pouches you have. I personally prefer webbing to molle vests as it allows you to keep cooler and it doesn't stop you feeling hits. Most people go for a molle vest though 'cos they look cool and require less work to adjust them properly. I would suggest that starting out, you get something cheap in Tan or Olive drab. Black is very easy to spot in woodland but plain colours are easier to find cheap pouches for and will work with any new camo you decide to get.