Absolute maximum for next week's shopping

Just done a few sums and the absolute maximum for next week's shopping, delivery and bags included cannot be more than £100.

I've got £339 in my bank account.
My monthly bills come to £239, that leaves me with exactly £100, can't even go £1 over unless Steve lends me the extra... pennies, yes, pounds definitely not unless Steve lends me it for a week.

In theory I've got another £20 in my savings accounts, but want to avoid using those if I possibly can.

Get paid again in 2 weeks so I'll be able to go back to saying to Steve that he can spend up to £115 each week again, but we've really got to go carefully with the shopping next week, even if it means that we just get stuff for Steve again.

I can make do if I have to... we've got a freezer full of potato stuff already so I can have that next week if I need to, we just need to be careful for one more week is all.