I take it that is porridge oats
If it were me I would just use your formula to cook as normal instead of cows milk (I seem to remember Scott can't have normal milk anyway - but I may be wrong).
I still use formula rather than cows milk to make cheese sauces, spinach pasta, etc. and they need to be boiled. I only drink semi-skimmed anyway so I think buying a pint of full fat for a small sauce isn't really needed.
I make Calums readybrek using formula and it gets to boil so the readybrek goes soft. Just to let you know that I only use the readybrek and in small amounts and add 2 small icecubes of fruit to it, especially as he has only been getting it 2 weeks. I will add more readybrek eventually.
I will be a bit trial and error until you get the right consistency anyway, Calum didn't like it at first - probably becasue I had too much RB in it.
HTH's