jogym have a look at the job description/person specification. On the person spec and/or advert, they will specify what qualifications, skills and experience are necessary. Interview questions will mostly be about making sure you have all those.
Look at the list of skills/experience you need, and think of examples of when you have demonstrated those well in the past. Giving a proper example rather than saying 'I would do x' is a lot better. If you work up an example in your head to cover everything that's required for the role, that's a good start, then it will all be at the front of your mind so you won't freeze and not be able to think of anything.
If they ask you a stupid question like 'what are your weaknesses', say something in a work environment that you used to feel you needed further development in. Not something you are/were rubbish at, but something that you felt a bit of extra knowledge or experience would help. Then say what you did to achieve that, what action you took to improve. That way you are not really saying a weakness as such, and you are highlighting your commitment to improving your own performance.
I wouldn't advise asking whether they have a sick pay scheme during the interview, it may give the impression you have lots of time off, which isn't good. That's the kind of thing you can find out if/when you get an offer of employment, which you can turn down if things like sick pay and other benefits aren't good enough.
Prepare some questions about the job, about the team you will be working in, about any changes or significant events coming up for the company, perhaps about further training, that kind of thing.
Remember they wouldn't be going to the trouble of interviewing you if they didn't think you could do the job.
Good luck!