No you alter your insulin dose, to match the carbs Oliver - so if you calculate the carbs as being 80g and you have a carb ratio of 1 unit for 10g, you would take 8u of Novorapid for that. Then you have to see if that works right for you. If your BG doesn't come back down to whatever it was before that meal and is higher, you need to increase it to (say 1 unit for 9g of carbs) or if it's lower than pre-meal then you'd need to reduce it (to say 1 unit for 11g of carbs)
Coming back to your levels - when you discover your BG is too high before the next meal - you need to take a 'correction dose' of insulin. I've always been told to correct down to 7.0 because that's a very safe level to begin with - plenty of room above a hypo but not 'too high'. If you try to correct down as low as 5 or something, that doesn't give anough scope for glitches. It really is best to use caution at every stage.
The recommended start point for corrections is that I unit of fast acting insulin will bring your BG down by 3.0 - ish. So if I was 10.0 before lunch, I'd work out the carbs - let's say I'm having a sandwich and it's 30g carbs, I'd take 3u of insulin for the sandwich and add 1unit on for the correction. So I'd shoot 4u. By 4 hours after that meal, my BG should be 7 (ish) again.
It all sounds rather complicated to start off with - that's why the courses take a week! Delivered a day at a time in bite-sized pieces and you learn shed-loads of things about the way your body works, and gently start putting all this theory into practice under the supervision of medical staff. Every body is NOT the same. Don't assume that what works for me or someone else will work for you.
Please don't try and learn all this immediately - do the online course if you can't get a face to face one soon and work through it to the end!
And there are meters that (provided they are set up properly with the correct info personally for you!) will actually do all the maths for you. You still have to calculate the carb value of what you are going to eat though. These meters (eg the Accu-Chek Expert or the Insulinx one) are ONLY available via your DSN. They are very expensive compared to a normal meter although they use the same type of strips so once you have it, the strips are available on prescription same as whatever ones you are using now. Very useful tools for us!
Hmmm I see from the DSFNE website, that for the South Tyneside NHS Trust, DAFNE is not available. However they may well have another course by another name that they deliver to their patients. You will have to ask the hospital because there's no info on their website. Don't despair though, because we have no DAFNE in my area either (Coventry & Warwickshire). But we most certainly do have an excellent course called CARBS-4-1.