Paddington is well-connected to other parts of London through the Tube and bus services. The easiest way to get around is through public transportation, which is relatively cheap and efficient. You can buy a one-day travelcard or use an Oyster card to save money. The estimated travel costs for this itinerary are around ££.
If you have more time, consider visiting other parks such as Hyde Park or St. James's Park. If you have less time, you can skip Camden Market or Little Venice boat ride. Alternatively, you can combine Regent's Park and Primrose Hill into one day and use the extra day to visit other attractions in London.