Need to service my car soon, on 50k miles. Do I just need to get oil, filter and air filter? anything else need dojng on these? This will be the first time I've done anything  on this car

partly depends on what was done previously, was it all done at as per the Ford list of items at all earlier services?

eg. I had a fiesta 1.6tdci and it said change fuel filter at 37.5K (i auume focus the same) .   I actually ignored the fuel filter until about 115k miles when the car started going into limp mode and cutting out which was cured with new diesel filter 

Same here, I think I've done the fuel filter twice in 125k miles, each time when the car tells me its needed. I waited 8 years to do the pollen filter,  that came out dirty enough and to be fair its so easy to do (though a bit fiddly first time) you might as well do it if it hasn't been done for a while. Brake fluid change supposed to be every couple of years but again I haven't ever done it on mine.  I always make sure the oil, filter and air filter are done more regularly than recommended.  And just because the service book is stamped, don't assume everything has been done as per the manual.

go here

https://www.etis.ford.com/vehicleRegSelector.do

put in reg. no. (assumes your car has always had same reg no and was new when registered in UK) and click Search. it should show all the details of your car.

then on left side near top click on 

FordService

Generate a FordService schedule

 

 

 

I bought the car on 38k from a ford franchise and it was serviced when I bought and stamped but not sure how much of a service they would have done? Prob don't need to do fuel filter or brake fluid etc

to be honest if was mine I would only do the oil and the oil filter.  and maybe the air filter but only if it visually looked like it needed it. I did my air filter first at about 120k but that was only because it looked like it might start breaking up and that would be a bit of a problem if it got sucked in.   I am only say what i would do on my car. I am not giving you advice . Disclaimer etc etc.

Thanks it's just the only car I've ever worked on myself was my old 406, just wanted to make sure there wasn't anything stupid I'd do/miss on the focus for a service, plus it's a diesel so wasn't sure if they need different services and items 

According to Haynes, fuel filter and air filter every 37000 or 3 years, Oil & filter every 6000 (Ford say 12000), pollen filter every 12,000. Timing belt every 62500 (Ford say 125,000 but don't risk that long, mine was hanging off after 80,000 lol), Drivebelt 100,000 or 8 years and brake fluid every 2 years, regardless of mileage.

The original 16 valve Tdci engine was prone to turbo problems if very regular oil and filter changes weren't adhered to. As Albert suggests, change your oil and filter every 6k miles max religiously and you shouldn't go far wrong. The sump drain design doesn't allow complete drainage and unfortunately always leaves a quantity of dirty oil which instantly mixes with the new oil when changed. The meagre engine oil capacity doesn't help either. There's plenty of info online about the foibles of this engine but don't be put off it's a great little engine if well looked after and you can get away with blanking off the EGR valve.