Right, now I have a better idea of where you are.
My advice would be:
1 Buy a really good 1/2" router. There are many recommendations on here - Triton DeWalt Festool Hitachi. Do a search for Router Recommendations and you'll get a surefire cure for insomnia. You don't have to skimp if you have a £300 budget! PM me if you want to know about Really Good Plans for a mortising jig Smile
2 Email
[email protected] and ask him for a back issue. I think it it is #5. You'll get plans for a Norm-type jig that is safer, MUCH easier to use and will give you excellent results. Right first time every time, to coin a phrase. Not just tenons either, but twin tenons, bridle joints, splines. Lots. You can buy the small amount of required hardware from Axminster, your local engineers' merchants, or, preferably, me.
You'll learn a lot, get great satisfaction and have bags of money left to buy other woody stuff! I promise.