best place is a motor factors!
here are all your local ones!
http://www.yell.com/ucs/UcsSearchAction.do?keywords=motor+factors&companyName=&location=Romford&x=4&y=17&ssm=0&scrambleSeed=35496210&M=0
you cant really bugger it up if your only doing a mini service!
just do as advised and buy a haynes from halfords
you should have a jack in your tool kit! along with wheel brace!
to do a mini service you dont really need one!
your car isnt lowered so you can still reach the sump plug!
just undo that and drain the oil into an old washing up bowl or something!
whilst that is draining - take of your air filter (and fuel if your doing fuel at the same time) and replace these!
use a spark plug remover and undo all the sparks - undoing 1 HT at a time if you not sure were each goes! and replace then hand turn the sparks as your putting them in first then just nip them up with ratchet. stops you cross threading a sparky
once the oil is drained take of the oil filter and top the new one up with fresh oil and lubricate the rubber seal before putting it on the car.
put your plug back in and top the oil up going bit at a time if your not sure how much to put back in! judge to start by how much you took out!
**service note - if your changing the HT leads and dizzy the take the dizzy off with all the HTs attached to the sparks put new dizzy on!
then transfer each HT to the same position as the previous one was.
turn the car over and let it run for a minute!
stop it and let it cool down for 5 minutes!
recheck your oil! and top up as required!
that should get you going for a bit
but best advise
BUY A HAYNES MANUAL