Google analytics and tag manager fixing for various client sites

We are a small agency and we need various events/goals set up and fixed using google analytics/google tag manager - they were installed by a previous employee and we need them all working and also to be shown how things are created so we can do in the future. It would be ideal if you could come to the office in Watford (15mins walk from the train station) This shouldn't be a very long job - we have 55 clients but not all of them have problems. Envisage maybe a week of work for an experienced individual. Currently assessing issues.