Having spent over 25 of the last 40 years as Non Resident I totally concur with all of cavortingcheetah's posts.
Yes you are liable for any mistakes but and it’s a big but, with a reputable company preparing your returns the IR tends to be far more amenable and almost understanding.
One thing I would suggest and that is to keep a very accurate diary with all necessary evidence of days in/out of the UK.
Whilst IR rules are not overly complex, they are open to creativity. A good consultant should exploit this to your advantage without any undue risk.
I’ve been audited on a couple of occasions without too much hassle because I had ALL documents/evidence/proof to back up my returns.
Mrs ZFT is currently going through a 7 year NR audit over some rental property and because she didn’t listen (do women ever?) she is having an interesting time!!
Only thing I can’t resolve is how to be declared Non Domicile. This would fix so many problems!!