procedure for getting tenant to pay money owed when have left property without giving full notice.

My tenant left the property 6 weeks before the cessation of her tenancy agreement giving only 2 weeks notice. As covered in her tenancy agreement I requested that she find a suitable replacement tenant to take over her contract or give a month's notice, inwhich time she was to make reparations to the property. She left after only 2 weeks, leaving damage, dirt and debris for me to deal with. I found a tenant to replace her 2 weeks after her vacating the premises and I had to use that 2 weeks to effect the repairs and clean the premises ready for the new tenant. This left me 2 weeks down on my income for the property.

I have used the deposit and have incurred some additional costs. I have also billed the tenant for the 2 additional weeks rent which would complete her one month's notice and would correspond with the date that my new tenant took over the tenancy of the property.

She is refusing to pay the additional 2 week's rent and the additional repairs bill.

Can you please tell me the procedure for claiming this money. Would it be through the small claims court? If so, is there a specific form?
Is there a set out procedure for me to follow in terms of records kept, letters sent to tenant etc. Does the value determine the method of collection.

During this tenant's term, she switched to DSS payments which were not payed directly to me.

I appreciate your help thank you.