Hi,
You may wana take a train from Changi Airport to Novena Station (the journey is around 1hr, you need to change the train twice, hence pls ask the passenger where should you change the train). Then I suggest you take a cab from there (ask the people around on where you could take a cab from the taxi stand). The taxi journey will be less than 10min)
Hope you both will enjoy your visit! :)
Below is the street directory link to the hotel, i hope it's correct!!!
Value Hotel Thomson