Suggestions

[Whole]

I have a big family to feed plus my kids love food, no fussy eaters. As the food prices gone up. Its getting difficult to stay in budget.

I used to spent £150 a week (5 people) £50 for petrol etc. but now i cant stay in this budget.

Lone parent work part time. Cant increase my hours because of kids responsibility.

We do not eat out not even on birthdays, Christmas. No holidays at all

Any suggestions to maintain an average lifestyle.

Depending on what you mean by 'an average lifestyle' you might not be able to do it on your budget unfortunately.

All you can do is increase your income (if you're on NMW you'll get a pay rise in April) plus there's lots of other demands for pay rises and make sure all your essentials like broadband and phones are as cheap as possible - you can get a social broadband tariff for £10-15 pm, also for phones, make sure you're on SIM only rather than 'full' contracts.

Look on Moneysaving Expert budgeting section and go through all the tips as lots of little savings can add up to a noticeable difference in your disposable income.

As for food, look at where you shop, what you buy and how much you waste.
You get a lot more bang for your buck if you shop in Aldi or Lidl, buy cheaper versions where the quality/taste is acceptable, buy on offer/super 6 for fruit and veg (also look at frozen as can be much cheaper), eat some things that are naturally cheaper to buy/make and waste as little as possible.

With 5 DC you're probably buying a reasonable amount of snacks, so have a look at Approved Foods if you can make it last without them binging like locusts or possibly To Good To Go, but that's more a way to get takeaway/coffee shop food cheaper than full price, and you can't choose what you buy, so isn't always a money saver, for example, Costa etc seems to be a lot of toasties, which aren't cheaper than making your own, even at the TGTG price.