Posted: 05/05/2016 at 14:03
The best thing to do during the first year with a new garden is to watch it grow to see what there is and when it does its thing. Mow the lawn and remove obvious weeds from borders but observe the rest and make notes and take photos to help you remember what you like and want to keep or what you don't like and want to lose and also what you want to add or change.
As stated, lavender needs trimming back once flowering finishes and you can cut the stems right back to the top inch of foliage. They don't regrow from bare brown wood so, if yours are particularly leggy or bald, think about removing them completely and replacing with younger, healthier stock or else disguising the bare legs with other plants. Lavender grows best in sunny, well drained, alkaline soils and doesn't need loads of nutrients so I doubt feeding it will help.
Roses need an annual prune and how and when this is done depends on what kind they are - shrub, climber or rambler. It's a bit late now for a major spring prune but it will still be worth going around each one removing dead twiggy bits, thin twiggy bits and any stems that are crossing and rubbing against another. While you're on, take off any remaining dead flowers or hips from last year, cutting back to a healthy leaf axil. Roses are hungry plants so give them an instant tonic with a drink of liquid tomato feed and then a handful of slow release special rose feed pellets. Keep dead heading through the season once they start flowering. Check the RHS site for advice on pruning for next year - https://www.rhs.org.uk/advice/profile?pid=186