Strewth. If you decide on a gas turbine there is a book titled "gas turbine engines for model aircraft" by Kurt Streckling,
isb 0951058991. This is a good primer on the subject with complete plans/instructions on how to build one at home.
If you go the pulse jet way just put the words in any decent search engine and you will find plenty of sites with plans.
They are very thirsty so you might want to consider using ordinary petrol for fuel.
Be warned though, they are very very noisy, so unless you live several miles from the nearest house you could have trouble with the neighbours.