Hi Colin
This is a tough one, we can all give our advise dependant on what's going on in our lives but at the end os the day, you know about your business and what the job offer is offering.
It is going to be dependant on a few things, as mentioned holidays, any pension and most of all actual take home pay.
Again as stated write a list down, what will you lose by going to work and what do you gain. Obviosly you lose a lot of freedom (depending on the job) but you also have to take into account your family and quality of life.
I went back to work part time 9 months ago, fri/sat nights 7pm-3am, it doesn't interfere with my business and brings in an extra £4-500 a month. I did it because business took a dip.
I do love working for myself as we all do, I like the freedom it gives me but what bugs me is the unpredictability that we sometimes get i.e. getting trapped on holiday and not working for a month.
At the end of the day, the decision is yours, just make the right one for you.
Regards
Martin