I can get a family lasagne for between £2.69 that is fine.
To cook one from scratch I need (Aldi):
1 lb mince £2.69
Jar passata 99p
some herbs from a jar that costs 99p
Onion 17p
Clove from garlic head that costs 17p
Packet of lasagne sheets 59p
Flour from a packet that costs 45p
1/2 pint milk 14p
You can get a packet of herbs much cheaper than a jar and you will use it for more meals. I tend to buy one packet of something like dried herbs or a tin every other shop, I don't buy them for a specific meal.
The same with the garlic, it will last months in the fridge and do at least 5 other meals.
You have flour so you could make lasagna or you could get some cheaper dried pasta. Tesco sells basic lasagne sheets for 35p
Don't buy a jar of passatta buy a carton, they are 35p in Tesco, but the supermarkets do try to hide them away from the jars.
Now assuming you did buy all of that you presumably bought a whole pint of milk so for the cost of some sausages and one egg you can make a toad in the hole, a packet of not nice sausages can be had for 70p, but if you want to use better ones it might be £2-3.
So cumberland sausages and another 1/2 pint of milk would be (using tesco again) £1.50 + 14p + £1 (th cost for 6)so for under £3 you have a meal for 4 people.
Aunt Bessies would cost you £1 per person, so at least £1 more.
But you still have lots of flour and 5 eggs, garlic, herbs to make a meal from. How about garlic and herb flat bread with scrambled egg?
Or buy some veg and make a Spanish omelette (a packet of frozen mixed veg is about £1).
Ok using your prices the initial lasagna is £6.19, but lasagna + toad in the hole + Spanish omelette is £10.83, so £3.27 per meal, but you still have garlic, herbs and flour left over. You will probably have some lasagna sheets too and maybe some frozen veg. In fact add another pint of milk and a packet of passatta and you can make a vegi lasagna for £0.63.
If you had used Tesco for your passatta and lasgna sheets your initial outlay is £5.31 and £8.95 for three meals with left overs, less if you use cheaper sausages.