what about 4 years integrated
phd course. is it more rewar-
ding than traditional phd

An integrated PhD course will probably provide a better training than a traditional 3 year UK PhD. The taught elements of the course may make your experimental work easier to manage. However it will be more expensive and takes an extra year to complete. If English is not your first language, an extra year of study may provide more time to improve your written English before writing your thesis.