"In terms of day to day management I would have control though wouldn't I?? Eg staffing, hours/days I work???
Not even that, necessarily.
ChippingIn and BeenBeta make some excellent points. My husband is a contracts solicitor with a lot of experience dealing with franchises for the franchisee and the franchisor. You can't generalise, you need to look at the franchise information pack and see what sort of commitment they require from you and the degree of control/support you will get. For example, if you run a car hire franchise or a franchise for a well-known fast food outlet, you may be required to have certain (long) opening hours, send your staff to be trained at HO (for which the franchisor may charge), etc etc. You may have to pay the franchisor for your marketing material and take part in money-off promotions even if this loses you money.
You may also find that you are bound into the franchise and have to keep paying the percentage to the franchisee even if your particular franchise fails.
You may need premises (which if you lease may again mean you are bound in even if your franchise has failed).
The key point really is that you need to speak to a specialist franchise lawyer/advisor. Someone else mentioned Business Link - that's an excellent place to start and they will be able to put you in touch with a recommended lawyer. The lawyer will be able to advise on the pros and cons. Remember that you may not be actually free to negotiate the terms of the franchise, but the lawyer can spot things that you may not realise the significance of.
The cost of the lawyer may seem a lot now, but it is very small compared to what you will be paying the franchisor and may well save you a fortune in the long run.