I'm due to have my period in 3days and tonight my partner and I had sex,can I take a hpt tomorrow morning?we have been trying to fall pregnant almost two years now.

No as it would be completely ineffective.
It can take several days for fertilisation to occur.

If you are due a period in three days, normally today would be a very ineffective date to try. Have you in two years discussed this with your doctor. Are you tracking your ovulation dates by methods such as temp change and the such. Are you refraining ( not having sex) during the less fertile times and having sex only during the most fertile dates.

Also I am sorry do you not understand Home Pregnancy Tests after two years ?

If you just had sex, it will not be effective to test for several weeks,

Since this time your period is due in 3 days, you may even have it, but most likely it will be light. It will be next month to see if you miss that period, and then if you miss it, you test then. About 3 weeks from now at the very earliest and normally that is even too early for a home pregnancy, test, but 4 days, sorry they don't work like that.

If you only had sex tonight, you would have to wait until your period is due next month for the test to be accurate.