When we had our Portage worker for DS1 she helped to teach us techniques to use with him, such as TEACHH and PECS.
She also provided an awful lot of practical help in terms of helping us to become aware of and apply for benefits, the incontinence service, accompanied us on the visits to special schools and helped us identify what we would be looking for/pertinent questions to ask, etc.
She also acted as an advocate for us and visited the assessment nursery at the CDC that he was attending to observe and give feedback to the staff, when we had concerns and was always a great 'sounding board' whenever we needed one.
She also made us aware of other areas of support, such as local 'step by step' nurserys and specialised events, this was great as it allowed me to make contact with lots of other parents with similar experiences.
Even now I still recieve correspondence from portage frequently and have the opportuntity to use a 'friends of Plymouth Portage' caravan for a reduced cost, which is on a site in Cornwall and has been fully fitted out for families with SN children, even though DS1's portage service finished around 2 years ago.
DS2 will be having his own Portage worker starting in September and although we no longer need the support and advice that we needed with DS1 (as we were very new to the world that is SN), we are very much looking forward to the different kind of support that will be offered, which will be more around physio and communication rather than managing behaviours.
So in answer to your question, Portage for my family is/was a bespoke service that was catered to our own indiviual needs and I should imagine that is what it will be to you.
However I am aware that although I have had a great experience with Portage, this hasn't always been the case for everyone on Mumsnet and perhaps the quality of provision, like most things SN can be somewhat of a postcode lottery.
I do hope that your experience is as great as ours though.
Best of luck with it.