You need to start by using a full disk encryption mechanism. Something like BitLocker for Microsoft or FileVault for Mac or any others.
That is your base line defense but it is certainly not enough for total protection.
To be perfectly honest, you need to change your behaviours in order to be very secure. For instance:
- If possible, do not travel with all of the code.
- Consider using a secure VPN to access your sensitive info (that leads to other threat vectors though).
- Limit your exposure in threat zones, keep your laptop with you.
- Do not hibernate your computer (always turn it off and on).
- Be alert in general.
- Change your passwords frequently.
- Never access public wifi
- Disable bluetooth and wifi (if possible and when not using it)
- You could also look into a remote wipe software/service (but it's not perfect).
- Disable Ad Hoc Connections as this is potentially a huge risk.