I was terrified of tearing, it was THE thing I was dreading about the birth which makes me smile in retrospect as the general pain of the contractions meant I didn't feel it when I did tear (2nd degree, no grazes) as it was all generally painful. Gas and air helped a lot.
As somebody else said, I think my birth was mismanaged too as my midwife just said "PUSH! We need him out NOW!" as if it were a major emergency which it turned out it wasn't (he had apgars of 9 and 9) so of course I did and that's why I tore because he shot out too quickly.
So if you speak to your midwife and tell her you're worried about tearing and would like her to ensure as much as she possibly can that the pushing stage is monitored (they can use a warm wet flannel on your perineum as the head crowns to help the tissues stretch) she will do what she can to help you.
But don't worry too much, you'll find that once you're in the last stages of labour you're in a different place, it's all consuming and your priorities will be different, you probably won't be even thinking about a tiny tear/graze, your focus will just be getting the baby out healthy and as quickly as possibly so the bloody pain stops! It probably won't even enter your mind.
And if you do tear, it isn't the end of the world. Immediately afterwards you'll feel so knackered and glad the pain has stopped, and you'll be focussed on meeting your baby, so amazingly you won't think about any soreness down there. You probably won't know you've torn til your mw tells you. If you need stitches, well, they do sting but if you use the gas and air it does take the edge off and you won't need many.
Afterwards your entire down there area will ache and be sore for a while anyway, but if you tear it will obviously make it slightly more sore- but nothing you can't cope with!! Take paracetamol for the first two or three days and be careful how you sit down/turn over it bed as I yanked my stitches turning over awkwardly whilst leaping up to see to my baby (he won't expire if you don't leap up the very second he starts to whimper, btw- took me a few months to realise that!)
And as everyone's said, pee in the bath, or direct some tepid water over the area when you wee. Take fybogel (stool softener) the first few days to help make pooing easier- can't recommend this enough! I didn't take arnica to help with bruising and pain but wish I had. Witch Hazel on a maternity pad can help with soreness too. Any stitches will dissolve within a week or two and quite honestly within 3 weeks ALL pain and soreness was gone and I felt back to normal (and ready for lurve, actually!)
Hope this helps.