Are there any bus or ship from Paris to London?

For bus, there is Euroliner (NationalExpress) coach services running directly from central Paris to central London... The fare are at GBP44 for a standard return while discounted fare (FunFare) start from GBP7 per way... The coach journey take approximately 8hours (Night Services available departing at late night and arriving at early morning)... For further information, you can check on www.nationalexpress.com
As far as I am aware, crusis services is avaliable from the coast of France to either Portsmonth or Dover... And you will be required to take your own trip down to the pier to catch the crusis/ferry services... And I think in many occation, the coach services would use the ferry services (depending on situation)...
Beside those option, you can also consider EuroStar which operate direct train services between London and Paris which take approximately 2hours 45minutes while their fare start from GBP75 (Depending on date)... You can check for further infomation at www.eurostar.com
While flying is not the option I would suggest as the fare could be similar to coach but the process is costly in term of time while the check-in early and accessing airport could end up taking up to around 6~7hours...