You have sort of answered your own question. If your unable to take a cut in hours/wages by employing someone until more work comes in, then your in a difficult situation.
Realistically, you will need to cover wages, extra insurances, any PAYE employer contributions, etc. There are all the Health & Safety issues to look into & then you have 3 or 4 weeks per year paid holidays to cover. Additionally, you also need to employ someone trustworthy & reliable - an unsuitable member of staff can do your business more harm than good.
I have opted to stay as I am though I could easily expand. (recently gave up 1 of my businesses as I just didnt want the stress or work). I choose NOT to take on more staff. I choose not to expand my business more. If I could do less, I would! In my opinion, life isnt about how much money we earn, its just something we do to earn some money to allow us to enjoy the rest of our life.
Think carefully before you make any big decisions.
GOOD LUCK