Good for you for wanting to have a go. Even if you get a template, which I understand can be very expensive, you'll need to practise first.
Don't expect to switch on and get a perfect job first time, and make sure that anything you are routering - practise or not - is well secured or clamped to stop it jumping around - that's half the battle in my experience.
And make sure your depth stop adjustment is correctly secured!
If you practice routering various shapes and depths, you'll quickly get an idea of whether you really have the knack for this sort of work or not. If you're really not comfortable with it, then the chisel isn't a bad idea - keep it sharp, take it easy, and remove little bits at a time.
When routering, remember that, if yours is a 1/4" router, the shank of the bits may flex slightly under pressure, causing it to 'jump' a little and leave uneven edges if you try and remove too much timber in one pass. A 1/2" router, which is usually a lot more expensive both for the machine and the bits, has 4 times the cross-sectional area of the shanks.
[quote] Its a DIY job so nothing for like £100 please [/quote]
routers are expensive and so are all the accessories and for good reason. they are precision instruments and trying to do it on the cheap is pointless frankly. you get what you pay for.
you can get a relatively cheap hinge jig from trend:
i've used one of these, the result is fine but a bit of a faff to set up compared to the more expensive hinge/doorframe jigs. so although they only cost £30-40 the hassle element may not make it worth your while investing in one - not at least unless you have a spare door to practise on first.