I develop on regtest, and only later test on testnet; my regtest folder is 18Mb in size. Regtest also has on-demand mining meaning I don't have to wait on the miners among other advantages.
My testnet3 folder is now 27Gb in size suggesting you should be able to accommodate it without problem. The full blockchain for mainnet is almost 250Gb. A second-hand ...
You can run your node in pruned mode if storage is your concern. Reduce Storage
If you want to try to use bitcoin on testnet you can use Electrum wallet.
Be sure to download it from their official website https://electrum.org/. (Do not download Electrum from another source than electrum.org, and learn to verify GPG signatures.)