Urban Spaceman,
Best solution would be to give a couple of builders a call and get them to quote, put the two quotes to the ec/ SM, requesting a motion on the agenda of the next general meeting to accept a quote for the works that are required.
You may also wish to contact a pest control company in the first instance to get the seagulls removed otherwise you could end up with bird lice inside the roof void, again grab two quotes and refer to ec or general meeting.
Mr S