It’s $200 / 67 = $3 per lot (=your £2.98 in round terms)
But since std lot is $10, You need = ( $3/$10 ) You want 0.3 Lots - ie your answer is nearly right (by coincidence only) but your working is wrong.
BUT you need to confirm that the “Lots” you are speaking of are Standard lots - worth £10 per pip ! I cannot see your broker account and this is essential.
TRY IT ON DEMO ! until you get the hang of it properly.
I recommend - you just do it on demo and work it out for yourself. !
It is really not hard and it is something every trader - even the very very newest, needs to be able to do in round figures, in their head without any doubt as to what their risk is !
just typing numbers into someone else’s spreadsheet - is simply Not helping you to learn !