To Fix or Not

Good afternoon all,

I hope you are all well.

My mortgage deal is coming to an end and I am curious as to what to do. I guess the reason I am asking this is because of everything going on at the moment with Brexit, and the uncertainty with everything in the country at the moment.

Is it worth fixing it again for the next few years as I did before when I first took out the mortgage? I like that idea of knowing how much money will be coming out each month for the next few years. My partner has recently become self employed so income is a little up and down until they get established. We also have two children to think about as well. I do like the security of being in a fixed rate mortgage.
I understand that being on a variable rate could mean I could pay less if the rate goes in my favour but there is always a chance of paying more as well.

Thanks in advance and look forward to your replies.