Here is the simplest approach that I can suggest. since you are only doing a small amount, I am keeping this a simple as possible.
1) You need...
K-meta
good quality wine yeast
Acid titration test kit
2 jugs, 1 stopper, and 1 fermentation trap.
All told, about $20 worth of supplies and equipment (not sure what this is in GBPs).
1) Crush the grapes I recomend that you use your (clean) feet.
2) Add about 1/8 teaspoon of the k-meta to the crushed grapes and mix well. This will sterilize the grapes.
3) Using a pasta strainer, strain the grapes into your jug. You could also use cheese cloth for this step. Push down on the skins to get as much juice as possible.
4) Check the acid level using the test kit. Most kits include simple to use instructions and the recomended level of acid (usually from .6 to .7 for white wines). Adjust the acid according to the instructions with either tartaric acid (to raise the acid level) or with bi-carbonate (to lower the acid level).
5) let the grapes sit for a number of hours (1/2 a day) and then add your yeast. Seal the jug with a stopper and fermentation trap. Mix some water with a little bit of the k-meta and fill the fermentation trap to the correct level.
6) let the wine ferment. After a couple of days, you should notice that gass is escaping from the fermentation trap (or a gurgling sound). After a couple of weeks, you should notice that the wine has cleared, and that there is a layer of sediment at the bottom.
7) decant the clear wine into another jug leaving behind the sediment. top off with a small amount of wine and reseal with the stopper and fermentation trap.
8) Sample it after several months. Find out if you can get more grapes next year!!!!
Note: This is the simplest approach that I can recommend. I do not suggest that this is the best approach. If you plan on doing more then, say a gallon, then I would recommend investing in better equipment and a "How to" book.