herpes doesn't affect your ability to conceive. Cold sores are type 1 herpes virus which is less active and dangerous than type 2 which causes genital to genital herpes.
Type 1 usually burns it's self out so doesn't usually cause problems during pregnancy.
Herpes is only really an issue if you get genital herpes for the first time close to birth. Baby will get some of your antibodies across the placenta to protect him; closer to birth there isn't time so baby may need meds, worse case scenario is you have a c section.
If it's worrying you, speak to the GU/sexual health clinic but the bottom line is, it's not too much of a problem,
HTH, hun
Rachael
xxx